SOHC.co.uk Forums > CB350/400
cb400-four speed.
Mikep328:
Yep! Good point!! I had something similar happen one day last year when the tool box cover slid back to obstruct the intake. Same symptoms - power went away under heavy load.
TrickyMicky:
Sorry Scifi, but 4th gear at 30MPH and you are what we used to call a 'con-rod bender'. Firstly, to get the seat open, use a 1/4DR 10mm extended socket on an extension bar, carefully work it up either side of the lock and locate the two nuts which hold the piece which fits into the lock. Check for obstructions to the air intake. Put a new set of plugs in. check ignition timing and valve clearances, plus of course oil level. Once the engine has reached running temperature, ride away changing up at about 6500 RPM in 1st and second, then for the remaining gears, wind it up to a minimum of 9500RPM. you should easily feel the change in acceleration as it reaches 7500RPM. If you rev it to at least 9500, when you change up, just barely feather the clutch lever, and only take the tension off the throttle cable. This will give you a very rapid gearchange leaving the engine revving at about 7000 in the next gear giving unbroken acceleration, that's why it's got a six speed box. PLEASE!!! do noit be guided by the road test figures that were bandied about in its day, there was a lot of backhanders from manufacturers to journalists for gleaming reports. 1ooMPH TT laps??? never in a million years, Malcolm Uphill only just managed that on a "carefully prepared" Triumph Bonneville in 1969. Outright speed testing conducted my the magazines of the day usually involved inflating the tyres really hard, brakes were backed off so no binding, the rear chain was cleaned and then lubed with something like 3 in 1 oil, and the rider would be wearing a skin tight leather one pice suit, lying flat on the tank with his left hand holding the left front fork. You met the nicest people on a Honda!!
Laverda Dave:
65mph😲. Something very wrong somewhere! You do have to rev them and they do thrive on revs.
The 400/4 should just top the ton unless of course it's a yellow one that some people may say were good for 130mph+ even against a force 10 headwind although I couldn't possibly comment......
Yetanotherbike:
Speaking from experience from my previous four 400/4's and presently restoring a 400/4, I'm with Laverda Dave all the way. My present 400/4 will be yellow for the reasons Dave has explained.
scifi:
Thanks Tricky Mick for the seat info. I managed to undo the lock and open the seat. The air Filter looks brand new, so I will have to investigate further.
If the weather holds today I will try some further tests. I have compared the speedo with a Sat-Nav and they are within 2 mph of each other.
Mine is a Red bike, but I have several litres of JCB Yellow Paint, if all else fails. . . !
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